Self-efficacy, decisional balance and stages of change for condom use among women at risk for HIV infection

HEALTH EDUCATION RESEARCH Theory & Practice Vol.13 no.3 1998 Pages 343-356 Self-efficacy, decisional balance and stages of change for condom use among women at risk for HIV infection Jennifer L. Lauby, Salaam Semaan 1, Abigail Cohen 2, Laura Leviton 3, Andrea Gielen 4, LeaVonne Pulley 3, Carla Walls and Patricia O'Campo 4 Abstract Theory-based models of HTV prevention need to be tested using appropriate measures with populations at high risk. Data from interviews with 4036 women recruited from facilities and randomly sampled from high-risk communities were used to examine the mediating variables specified by the Transtheoretical Model (TM). The analysis aimed to test the reliability of brief self-efficacy and decisional balance measures, assess the relationships of these measures to stages of change for condom and contraceptive use, and examine the extent to which these findings are consistent for women interviewed in different settings. The results indicated that the scales measuring self-efficacy and advantages (pros) of the behaviors were moderately to highly reliable, while those measuring disadvantages (cons) were much less reliable. Results were similar for women recruited from community and from facility settings. Possible explanations for the low reliabilities for cons were examined. Significant differences in mean scores by stage of change were found for all measures of self-efficacy, pros and cons. These findings are consistent with patterns predicted bytm. Philadelphia Health Management Corporation, Philadelphia, PA 19102, 'Centers for Disease Control and Prevention, Atlanta, GA 30333, family Planning Coundl, Philadelphia, PA 19102, 'University of Alabama- Birmingham, Birmingham, AL 35294 and 4 Johns Hopkins University, Baltimore, MD 21205, USA Introduction In the face of the growing epidemic of HTV infection among women, theory-based models of prevention need to be tested using appropriate measures with populations at highest risk for infection. In 1995 women, accounted for 18% of newly diagnosed AIDS cases in the US (CDC, 1995) and this proportion is likely to increase over time. Women at highest risk for infection include those who inject drugs, have a partner who injects drugs, exchange sex for money or drugs, or have more than one sexual partner. Women who reside in communities with high rates of drug use and poor health conditions, such as a high prevalence of sexually transmitted diseases, are also at risk if they are sexually active and do not consistently use condoms. In response to the growing threat of HTV7AIDS infection in women, the Centers for Disease Control and Prevention funded a multi-site intervention research program for women at risk for HTV transmission and those already infected. The Prevention of HTV in Women and Infants Demonstration Project (WTDP) promotes the use of condoms to prevent the spread of HTV, and helps women make informed decisions about childbearing by improving their access to and use of contraceptive methods, including condoms. Both the design of the intervention components and the evaluation methodology for this project are based on Prochaska and DiClemente's Transtheoretical Model of Behavior Change (Prochaska and DiClemente, 1983, 1984, 1986; Prochaska et al., unpublished). This model, sometimes called the Stages of Change Model, asserts that behavior Oxford University Press 343

J. L. Lauby et al. change occurs as a gradual, dynamic process in which individuals move through five stages. According to the model, specific cognitions, including self-efficacy and decisional balance [i.e. perceived advantages (pros) and disadvantages (cons) of the behavior] are associated with movement from one stage to the next. In this paper data from the WIDP baseline interview with 4036 women were used to examine the mediating variables specified by the Transtheoretical Model (TM). The purposes of this analysis were to: (1) test the reliability of brief self-efficacy and decisional balance measures for women at risk for HTV infection, (2) assess the relationships of these measures to stages of change for condom and contraceptive use, and (3) examine the extent to which these findings are consistent for women interviewed in different settings and with different HTV risk profiles. The stages of change in TM are a temporal sequence which describes when shifts in attitudes, intentions and behaviors occur (Grimley et al., 1993). The five stages are: precontemplation (i.e. not even thinking about adopting the behavior), contemplation, ready-for-action, action and maintenance (i.e. practicing the behavior consistently for at least 6 months). Progression through the stages is not always linear, and individuals may cycle back and forth across the stages before arriving and remaining in maintenance. The model describes how attitudes and beliefs, including selfefficacy and decisional balance, change in predictable ways as individuals move through the stages. For example, the model suggests that for people in the precontemplation stage, the cons of the preventive behavior are higher than the pros and self-efficacy is low, while for those in maintenance, the pros are higher than the cons and self-efficacy is high. If, as the model suggests, changes in selfefficacy and decisional balance precede behavior change, they are possible mediators through which interventions could promote movement through the stages toward maintenance. The concept of self-efficacy is a component of Bandura's (1977) Social Learning Theory defined as individuals' confidence in their ability to execute actions required to sustain behavior. Several studies have employed the concept of self-efficacy to explain the adoption of various health behaviors (O'Leary, 1985; Bandura, 1990). Recently, researchers have examined the relationship between self-efficacy and utilization of condoms. Brafford and Beck (1991), in a study of condom use among college students, found that individuals who used condoms regularly had higher levels of self-efficacy. Brien et al. (1994) found that selfefficacy was significantly lower for non-users of condoms, who tended to lack confidence in their abilities to discuss and negotiate condom use, than for consistent users, who felt secure in their abilities to communicate with their partners about condom use. Wulfert and Wan (1993) tested a model in which self-efficacy functioned as a mediator between other psychological factors and condom use. Their results revealed that self-efficacy operated as a central mediating variable through which factors, such as outcome expectancies and peer group comparison, influenced condom use. The assessment of perceived advantages (pros) and perceived disadvantages (cons) of health behavior change originated from Janis and Mann's (1977) decision-making model which proposes that 'a balance sheet of comparative gains and losses is critical' to the decision-making process. Velicer et al. (1995), building on this model, found that measures of pros and cons were useful in distinguishing between people at different stages of change for smoking cessation. Prochaska et al. (1994) examined the relationship between decisional balance and the stages of change across 12 problem behaviors (e.g. smoking cessation, quitting cocaine, safer sex, condom use, exercise acquisition, mammography screening, etc.). They found a consistent trend across all 12 behaviors: the cons for changing problematic behaviors were higher than pros for individuals in precontemplation, while the pros were higher than the cons for individuals in the action stage. In a re-analysis of these data, Prochaska (1994) examined the amount of increase in the pros and decrease in the cons associated with the movement of an individual along the stages of change. He found that in 10 344

Self-efficacy/decisional balance for condom use out of 12 problem behaviors, the increase in the pros was twice as large (averaging 1 SD) as the decrease in the cons (0.5 SD) during a health behavior change from precontemplation to action. Although cross-sectional data cannot confirm this, these results suggest that increasing perceived advantages may produce a stronger effect on health behavior change than reducing perceived disadvantages. Previous applications of TM have often focused on changes in individual activities, such as smoking cessation or weight loss, that had to do with giving up unhealthy behaviors. Attempting to change sexual behavior, such as increasing the use of condoms, presents somewhat different challenges. First, because of the private nature of the behavior, it is more difficult both to deliver prevention messages and to measure behavior change. Second, sexual activity may be more difficult to change since it is perceived as an unconsciously motivated behavior that is difficult to control (Prochaska et al., 1992). Third, because sexual activity involves two people, changing the attitudes of one member of the couple may not be sufficient to produce movement along the stages of change. Thus it is essential to test whether TM is a useful tool in designing and evaluating interventions that focus on changes in sexual behavior, particularly for understudied populations such as women at high risk for HTV transmission. In order to test the model and use it to evaluate the WIDP intervention, appropriate and reliable measures were needed. In a recent paper (Galavotti et al., 1995), WIDP investigators described the initial operationalization of constructs from TM for the measurement of condom and contraceptive use. A pilot test of the proposed scales was conducted on a sample of 296 women at high risk recruited from homeless shelters, drug treatment facilities, and areas with high rates of drug use and prostitution. This analysis identified five items with acceptable factor loadings for each of nine proposed scales (pros, cons and self-efficacy for each of three behaviors: contraception, condom use with main partner and condom use with other partners). Reliability, as measured by Cronbach's a, was very good, with coefficients ranging from 0.93 to 0.81 (Galavotti et al., 1995). Analysis of variance (ANOVA) indicated that self-efficacy scores rose significantly with stage of change, and decisional balance shifted significantly for contraceptive use and condom use with main partner, but was not significantly related to condom use with other partners. Although the measures developed in the pilot test demonstrated good psychometric properties, they had to be revised for use in the WIDP interview instrument because they were too long and, to some extent, too complicated to be included in a street interview. The questionnaire needed to be as short and simple as possible to collect valid data from women at risk, including those who use drugs, those who exchange sex for money or drugs, and those in high crime areas, who would not be willing or able to complete a lengthy interview. In order to reduce respondent burden, each of the nine scales developed in the pilot study was reduced from five to the three or four items with the highest factor loadings. To facilitate ease of response, instead of using a five-point Likert scale, each item was asked as a two-part question and the scoring of the decisional balance items revised to a three-point scale. This paper describes the reliability of the revised measures and examines their relationship to stages of change. In addition, because data were collected from a large sample of women interviewed in a variety of high-risk settings, we were able to test the reliability of the measures for specific subgroups. These analyses illustrate important considerations in instrument development, and help evaluate the applicability of TM to changes in sexual behavior among women at risk for HTV infection and transmission. Methods Data source and study sample The data reported here were collected as part of the baseline survey of the WIDP intervention research project that serves women who are either 345

J. L. Lauby et al. at high risk for HTV infection or unintended pregnancy or who are living with HIV infection. The WIDP is being implemented simultaneously in both community-based and facility-based settings in an effort to determine the feasibility and effectiveness of applying TM in a variety of settings to promote behavior change in women. A major component of the intervention is the stage-based encounter, in which project staff tailor their interactions to a woman's needs as reflected by her readiness to change. The community sites use a community mobilization framework to build support for the diffusion of messages and to help change social norms. The facility sites provide a series of intervention sessions for the women enrolled in the project. For the community-based survey, a site-specific randomized sampling plan was used to recruit women from geographically defined communities. Sampling was done in stages: (1) micro-sites where women might be found, such as shops, restaurants, street corners, parks and residential areas, were enumerated and then randomly sampled; and (2) individual women were randomly approached to be interviewed at each selected micro-site, following a site-specific sampling strategy, until the required number of eligible women were interviewed. In the facility-based research projects, convenience samples of women were interviewed in homeless shelters, drug treatment centers, family planning clinics and HTV/AIDS primary care clinics. Data from 4036 women were collected as part of the baseline survey conducted before intervention implementation. Baseline data from the community-based sites were collected during the winter and spring of 1993. Women between the ages of 15 and 34 who had engaged in vaginal sex in the previous 30 days were eligible for inclusion in the survey. A total of 2864 women were interviewed at community-based sites: 479 from Philadelphia, 900 from Pittsburgh, 591 from San Francisco, 458 from Portland and 454 from Alameda County. Baseline data from the facility-based sites were collected from spring of 1993 through fall of 1994. Women between the ages of 15 and 44 were eligible to be interviewed. As many of the women seen in facility settings are over 35 years old, a wider eligible age range was used in order to recruit sufficient numbers of women from these settings. The facility-based sample included 585 women from Philadelphia, 364 from San Francisco and 227 from Baltimore. All sites used an instrument with a common core of questions that was administered in person by interviewers after obtaining informed consent. Women were asked only those sets of questions that pertained to their situation (e.g. women who had been sterilized or were using an IUD or Norplant were not asked about self-efficacy for birth control). Thus the number of respondents in the analysis varied by question topic. Study variables Three main outcome behaviors were examined in this paper: use of birth control, use of condoms with a main partner and use of condoms with other partners. For each of these three behaviors, three scales were developed: self-efficacy, perceived advantages (pros) and perceived disadvantages (cons) of the outcome behavior. Birth control was defined as a method used to prevent pregnancy that requires some consistent action on the part of the woman and her partner. This definition includes the use of pills, diaphragms, condoms, spermicides or sponges, but does not include sterilization, intrauterine devices or Norplant. Condom use was defined as a male partner's use of condoms during vaginal sexual encounters. Women who identified their male sex partner as a 'main' partner, like a husband or boyfriend, were classified as having a main partner. An 'other' partner was any man, other than a main partner, with whom the woman had vaginal sex. Stages of change Three ordinal variables were used to measure stages of change for birth control, condom use with main partner and condom use with other partners. Each consisted of five stages: precontemplation, contemplation, ready-for-action (preparation), action and maintenance. Precontemplation was defined to include women who had no inten- 346

Self-efficacy/decisional balance for condom use tions of consistently using birth control or condoms in the next 6 months. Women in contemplation intended to consistently use birth control or condoms in the next 6 months, but had not yet made a commitment to do so. Women in the ready-foraction stage had intentions to start using birth control or condoms consistently in the next month and had used them inconsistently in the past 6 months. Women in the action stage had used birth control or condoms consistently for less than 6 months. Women in the maintenance stage had used birth control or condoms consistently for 6 months or more. Consistent use was defined as use every time the woman had vaginal intercourse. Self-efficacy The three scales measuring self-efficacy were constructed as continuous variables with a higher score indicating greater perceived self-efficacy. Selfefficacy for condom use with main partner and for use of birth control were measured by the sum of three items each (scale score range = 3-15), while self-efficacy for condom use with other partners was measured by the sum of four items (scale score range = 4-20). For each item the respondent was first asked whether she 'could or couldn't' perform the specified behavior, such as 'put off sex if you didn't have birth control with you', and then asked to specify whether she was 'very sure' or 'somewhat sure' that she 'could or couldn't' perform that behavior. Responses from both questions were used to score each of the items on a five-point scale: 5 = very sure she could; 4 = somewhat sure she could; 3 = don't know/not sure; 2 = somewhat sure she couldn't; and 1 = very sure she couldn't. Because reliability analysis requires complete data on each item, respondents who had missing data on any item were excluded from the analysis of that scale. The proportion of the sample that had missing data on the selfefficacy scales was small, ranging from 1.4% for condom use with main partner to 7.5% for use of birth control. Decisional balance For each of the three scales that measured pros and the three scales that measured cons of the outcome behaviors, we constructed a continuous variable that was scored from 3 to 9, consisting of the sum of three items. The higher the score on the pro scales, the more positive the attitude toward the behavior, while the higher the score on the cons scale, the more negative the attitude. The respondent was asked to indicate whether she believed that each of the three items was an advantage (for the pros scale) or a disadvantage (for the cons scale) associated with the specified outcome behavior. If she answered 'yes', she was then asked to indicate the importance of the specified advantage or disadvantage in her decision to perform the behavior. The potential responses were 'not at all important', 'somewhat important' or 'very important'. Responses from both questions were used to score each of the items on a threepoint scale: 3 = yes and very important; 2 = yes and somewhat important; 1 = no or yes and not at all important. Respondents who failed to answer an item or who answered 'don't know' were excluded from the analysis of that scale. The proportion of the sample who were excluded for these reasons ranged from 7.3% for pros of condom use with main partner to 10.6% for cons of use of birth control. Socio-demographic and risk variables Several socio-demographic and risk variables were used to describe the sample and to examine whether the properties of the scales differed for various subgroups of the study sample. Socio-demographic variables included age, education, ethnic group, marital status and living with spouse/partner. Economic variables included receiving income in the year prior to data collection from the following sources: a job, welfare or from a spouse/partner. For this paper, the indicator of risk characteristics for HIV infection was a dichotomous variable that identified women who had at least one of the following risk factors: had ever injected drugs; had ever exchanged sex for something of value including food, shelter, money or drugs; had used crack or cocaine in the 30 days prior to data collection; or had more than one sex partner in the past 6 months. In addition, a woman was considered 347

J. L. Lauby et al. to be at risk if she reported that her main partner had one or more of the following risk characteristics: had ever injected drugs; had sex with men or with other women; had ever been to jail or prison; or was HIV-positive. Statistical methods We first examined socio-demographic characteristics of all women in the sample and by site of data collection: community-based sites (n = 2864), general facility-based sites (n = 945) and HTV/ AIDS facility site (n = 227). Since one of the three facility-based sites recruited only HIV-positive women, we examined the characteristics of its sample separately. The samples from the other sites included very few women who reported being HIV-positive: six of the 2864 women from community-based sites and 21 of the 945 women from facility sites. One-way analysis of variance and the % 2 statistic were used to test for significant differences between samples. Subsequently, Cronbach's a, a reliability coefficient measuring the internal consistency of a scale, was assessed for each of the nine scales. A high a is an indication that the items are measuring a unitary construct. Correlations between items for each scale and the ratio between the largest and smallest correlation were examined. Ideally, scale items should be only moderately correlated with each other and the correlations should be similar, yielding a ratio between the largest and smallest of close to 1.0. Reliability analysis was also done separately for each of the three site sub-samples. Finally, we examined the relationship of each scale to stages of change. For ease of interpretation and comparison between scales, the raw score for each scale was transformed into a standardized T-score (mean = 50, SD = 10). Multivariate analysis of variance (MANOVA) was used to examine whether mean scores on the decisional balance scales (pros and cons) differed for women in each of the five stages of change. One-way analysis of variance (ANOVA) and the Scheffe test for post hoc comparisons were used to examine the pattern of differences between stages for each of the self-efficacy and decisional balance scales. Results Description of the sample Demographic and risk characteristics of women in the sample are presented in Table I. The majority of the women who participated in the study were African-American (80%) and over half (56%) were 25-34 years of age. Most of the women (73%) received income from public assistance in the past year and 41% received income from a job. Approximately three-quarters of the women had never married. Most of the women (78%) had a main partner, 37% lived with their spouse or partner and 49% reported receiving income from their partner. A majority of the women (70%) were identified as having risk characteristics for HTV infection. The primary behaviors identified as placing them at risk were having had more than one partner in the past 6 months (36%) and ever exchanging sex for drugs or money (25%). The comparison of characteristics by recruitment site shows that those in the community sample tended to be younger than those in either of the two facility samples, primarily due to different age eligibility criteria. Women in both facility samples had lower educational attainment, were more likely to be receiving welfare and were more likely to have HTV risk characteristics than those in the community sample. Reliability analysis As described in Methods, nine scales were developed for this study to measure self-efficacy, and pros and cons for contraceptive use, condom use with main partner and condom use with other partners. Focusing first on self-efficacy, Table II provides the means ± SD for each item and each scale, as well as the Cronbach's a for each scale. On each of the items included in these scales, over 50% of the women indicated that they were confident in their ability to follow through on the use of contraceptive and condoms. Thus the score ranges were skewed towards the higher levels with all mean scores above the mid-range of the scale. For birth control use, the three-item scale had a moderate level of reliability (a = 0.65). The scale 348

Self-efficacy/decisional balance for condom use Table L Demographic and risk characteristics of sample by recruitment site (%) Characteristic Community sites General facility sites HIV-positive facility site Total sample (n = 2864) (n = 945) (n = 227) (n = 4036) Age* 15-19 20-24 25-29 30-34 35-44 Education* <HS grad HS grad >HS grad Ethnic group African-American White Hispanic other, mixed Marital status* married separated/divorced/widowed never married Live with spouse/partner Have main partner* Income from job* Income from welfare* Income from spouse/partner HTV risk characteristics* ever used IV drugs* crack used last 30 days cocaine used last 30 days* partner's risk behavior* > 1 partners last 6 months ever exchanged sex for monev/drue 17 25 27 32 0 36 47 17 80 12 2 6 13 17 70 39 83 44 68 50 64 9 31 14 16 33 s* 19 6 14 22 30 29 48 36 16 74 15 7 4 10 21 69 29 68 35 86 50 82 28 45 27 38 47 43 1 11 18 34 37 52 34 14 93 5 1 1 7 28 65 32 59 24 85 41 84 54 29 46 25 14 30 13 22 25 31 9 40 44 17 80 12 3 5 12 19 69 37 78 41 73 49 70 16 35 20 19 36 25 Difference between community sites and other sites significant at P < 0.01 measuring self-efficacy for condom use with a main partner showed good reliability (a = 0.80), as did the scale for other partner condom use (a = 0.84). The correlations between the items ranged from 0.37 to 0.64, and the ratio between the largest and smallest correlation was 1.07 for general contraceptive use, 1.15 for condom use with main partner and 1.33 for other partners. Similarly, Table III includes the item and scale statistics for each scale measuring the pros and cons of using birth control and condoms. The means of all the pro items were above the midpoint for the scale, while those for the con items were all below the midpoint for the scale, indicating that in general the perceived advantages of birth control and condoms were rated as more important for decision-making than the perceived disadvantages. The pro scales had greater internal consistency than the cons for all three outcome behaviors. Cronbach's as for the pro scales fell in the moderate to good range (0.64-0.80), while the as for all three con scales were quite low (0.41-0.47). Interitem correlations ranged from 0.81 to 0.33 for the pro scales and from 0.28 to 0.10 for the cons. The ratio of the largest to the smallest correlation for the pro scales was 1.47 for birth control, 1.64 for 349

J. L. Lauby et al. Table IL Characteristics of self-efficacy scales: mean, SD and Cronbach's a Scale item: 'How confident are you that you could use...' Mean SD Cronbach's a Birth control use 1 If you didn't have it with you 2 If you had been using alcohol or drugs 3 If your partner got angry about it Condom use with main partner 1 If you had been using alcohol or drugs 2 If you were really turned on 3 If your partner might get angry or upset Condom use with other partners 1 If you had been using alcohol or drugs 2 If you were really turned on 3 If you didn't have condoms with you 4 If the man might get angry or upset 2706 2997 1279 11.73 3.91* 3.68 4.18 10.25 3.40 3.22 3.64 15.58 3.77 3.81 3.85 4.15 2.46 1.51 1.58 1.41 4.32 1.67 1.75 1.68 4.99 1.56 1.58 1.52 1.39 0.65 0.80 0.84 Item means range from 1 to 5: 1, very sure couldn't; 5, very sure could. Table in. Characteristics of decisional balance scales: mean, SD and Cronbach's a Scale item Mean SD Cronbach's a. Birth control use Pros 2663 1 Using birth control gives sense of control 2 Lets you have sex without worrying about getting pregnant 3 Keeps partner from worrying about you getting pregnant Cons 2619 1 Using birth control makes sex feel unnatural 2 It is too much trouble 3 It causes health problems Condom use with main partner Pros 2802 1 Makes you safer from disease 2 Protects partner from disease 3 Makes you safer from pregnancy Cons 2797 1 It is too much trouble 2 Makes you rely on partner's cooperation 3 Makes partner think you do not trust him Condom use with other partners Pros 1213 1 Makes you safer from disease 2 Makes you safer from pregnancy 3 It is easily available Cons 1180 1 It is too much trouble 2 Makes you rely on the man's cooperation 3 Makes partners angry or upset 6.76 2.34* 2.19 2.21 4.18 1.33 1.16 1.70 7.05 2.47 2.50 2.03 5.03 1.36 1.98 1.71 7.84 2.72 2J9 2.68 4.49 1.20 1.94 1.38 2.09 0.89 0.94 0.90 1.44 0.68 0.50 0.91 2.17 0.81 0.80 0.95 1.78 0.70 0.93 0.90 1.67 0.65 0.89 0.66 1.52 034 0.94 0.73 0.65 0.41 0.80 0.47 0.64 0.42 Item means range from 1 to 3: 1, not at all important; 3, very important. 350

Self-efficacy/decisional balance for condom use Table IV. Reliability coefficients fryrecruitment site: Cronbach's a Characteristic Total sample Site Community General facility HTV-positive facility Self-efficacy scales birth control condom use with main partner condom use with other partners Decisional balance scales birth control pros cons condom use with main partner pros cons condom use with other partners pros cons 0.65 0.80 0.84 0.65 0.41 0.80 0.47 0.64 0.42 0.66 0.82 0.85 0.65 0.41 0.81 0.46 0.64 0.40 0.61 0.76 0.82 0.65 0.37 0.78 0.50 0.61 0.43 0.70 0.73 0.79 0.60 0.52 0.72 0.40 0.67 0.54 condom use with main partner and 1.44 for condom use with other partners. For the cons, the ratios were 1.74 for birth control, 1.35 for condom use with main partner and 2.67 for condom use with other partners. In order to test whether the scales were equally reliable for women interviewed in different settings, a coefficients for the three types of sites were compared. On the whole, the coefficients followed the same patterns with only slight variations across sub-samples (Table IV). Thus the scales showed similar reliabilities for women recruited in community settings, and for women at higher risk and HIV-positive women recruited at service facilities. These results indicate that scale characteristics that were adequate for reliably measuring the pros were not adequate for the cons, perhaps because the cons form a more complex construct. There are several possible ways the con scales could be revised to address the complexity of the construct and thus increase reliability. These include increasing the number of items per scale, increasing the range of scoring for each item, and increasing the scope of the items to address a wider range of disadvantages and to improve the scale's relevance for women in a variety of life situations. Each of these possibilities was explored using available data. Expanded five-item con scales were available for a sub-sample of respondents from the general facility sites who answered a supplemental set of questions in addition to the standard interview (n = 101). The five-item con scales each included two additional items from the scales used in the pilot study. Analysis of this sub-sample showed improved reliability coefficients for the five-item con scales: 0.51 (versus 0.41 for the three-item scale in this study) for birth control use, 0.72 (versus 0.47) for condom use with main partner and 0.54 (versus 0.42) for condom use with other partners. Thus increasing the number of items did improve reliability, but did not approach the high as obtained for the self-efficacy and pro scales, or for the five-item con scales in the pilot study (as = 0.81-0.87). The use of a three-point scale to score each item may have limited item variance and so reduced inter-item correlations. This was tested by creating a four-point scale, separating the 'no' response from 'yes, not important'. While this change did increase the variance of item scores, it did not increase the reliability coefficients. To examine whether the reliability of the con 351

J. L. Lauby et al. Tbble V. Percentage distribution of stages of change for contraceptive use and condom use Stage of change Behavior Birth control (n = 2361) Condom use with main partner (n = 2925) Condom use with other partners (/I = 1213) Precontemplation Contemplation Ready for action Action Maintenance 28 10 17 6 38 60 9 13 5 13 22 11 26 10 31 scales varied for women in different life situations, we divided the sample into groups based on age and risk for HTV infection and repeated the reliability analysis within these smaller groupings. Also, because the responses to cons items may depend on the type of contraception used, women were grouped by current birth control method to test reliability of the birth control scales. To test the reliability of cons for condom use with main partner, women were grouped by the consistency of their condom use and length of the relationship with their main partner. The reliability of cons for condom use with other partners was compared for women who had and had not exchanged sex for money or drugs, those who had and had not ever had an STD, and those with one and more than one sexual partner in the past 6 months. This analysis indicated that although some subgroups had slightly higher reliability coefficients than others, the differences were not large. Therefore, differences in life situations do not seem to be the main explanation for the low reliability coefficients for the con scales. Age and HTV risk characteristics appeared to affect scale reliability for condom use with other partners. Women 25 years and older had a higher reliability coefficient (0.46) than women under 25 (0.28). Women with at least one HTV* risk characteristic had an a of 0.43 on this scale while that for those not at risk was 0.27. Those who did not presently use any birth control had a higher a (0.43), compared to women who used either the pill (0.24) or condoms (0.29), on the birth control con scale. The less frequent the use of condoms with a main partner, the higher the a on cons for condom use with a main partner (0.52 versus 0.42). Women who had exchanged sex had a higher a on the cons scale for condom use with other partners (0.47 versus 0.36). The other variables that were analyzed had no impact on scale reliability (differences in as of less than 0.10). In general, women with HTV risk characteristics and those who did not use birth control or condoms had higher as, perhaps because they tended to have higher cons scores and a greater variance for each item. Women at less risk tended to disagree with most con items, yielding low item variance and low inter-item correlations. These findings suggest that the con scales might be improved through increasing the number of items and through the addition of items that produce a wider range of responses, particularly among women at lower risk. Relationship to stages of change According to TM, self-efficacy and decisional balance vary by stage of change. Thus one measure of the validity of the model for the target population is whether these scales display the expected relationship to stage of change for the behavior measured. Table V displays the distribution of the sample by stage of change. Over 40% of women were in the action and maintenance stages for birth control use and for condom use with other partners. However, only 18% of women were in action or maintenance for condom use with main partner and 60% were in the precontemplation stage. 352

Self-efficacy/decisional balance for condom use Birth Control Lisa Pius Cons Btrth Control Um Condom Usa With Other Partnere RFA Stag* of Clung* Condom U*e With Other Partner* Fig. 1. Mean self-efficacy for birth control and condom use by stage of change. PC, precontemplation; C, contemplation; RFA, ready-for-action; A, action;, M, maintenance. RFA Sag* of Chang* Fig. 2. Mean pros and cons of birth control and condom use by stage of change. PC, precontemplation; C, contemplation; RFA, ready-for-action; A, action; M, maintenance. Analysis of variance indicated that for all three behaviors, self-efficacy scores increased significantly with stage of change (P < 0.05 in all cases) (Figure 1). Post hoc comparisons, using the Scheffe test, indicated that self-efficacy for birth control was significantly lower for women in precontemplation and contemplation than for women in the other three stages. For condom use with main partner, all groups were significantly different from each other, except for ready-for-action and action. For condom use with other partners, all groups were significantly different from each other, except for contemplation and ready-for-action. Decisional balance measures showed significant differences by stages of change for all three behaviors (MANOVA, P < 0.01) (Figure 2). Using the Scheffe test, significant differences were found between precontemplation and contemplation for all three pro scales, with a leveling off after the ready-for-action stage. The three con scales showed a more gradual decline by stage. Those in precontemplation, contemplation and ready-for-action had 353

J. L. Lauby et al. significantly higher cons scores than women in action and maintenance. According to TM, a crucial point for behavior change is when pros outweigh the cons. In our sample, the cons standardized 7-scores are much higher than the pros for those in precontemplation. The cross-over between the two scores occurs at the ready-for-action stage for birth control and at the contemplation stage for both condom use behaviors. Discussion This study examined the internal consistency and validity of certain elements of TM as applied to contraception and condom use. The measures tested in this study were developed for an interview survey conducted in street and facility settings with women at high risk of contracting HTV due to their sexual or drug use behaviors, and women already infected with HIV. The results of these analyses provide meaningful information on measuring key mediating variables and their relationship to the stages of behavioral change. The large sample made it possible to compare the reliability of the measures for subgroups of women who differed on place of recruitment and risk factors for HTV infection. The mediating variable of self-efficacy has often been shown to be an important predictor of behavior change (O'Leary, 1985; Bandura, 1990) and this study is no exception. Self-efficacy increased with the stage of change for each of the three behaviors in question. Moreover, self-efficacy showed moderate to good internal consistency depending on the behavior in question. We conclude that for the three behaviors of interest, the self-efficacy scales developed here reflect a valid unitary construct. The second mediating variable, the advantages of the behavior (pros), also were related to stage of change as specified by TM. Mean pro scores were higher for women in the later stages of change for birth control, for condom use with a main partner and for condom use with other partners. The ratings of advantages, like the selfefficacy items, showed moderate to good internal consistency, indicating that they also reflect a unitary construct. As assessed with a three-item scale, the third set of variables, the disadvantages of condom use (cons), does not reflect a single construct. The measures of internal consistency for all three behaviors were low. Nevertheless, the con scales behaved as TM predicted; women who were in the action and maintenance stages tended to rate the advantages of the behaviors more highly than the disadvantages, while for women who were in precontemplation the reverse pattern was true. It is interesting to speculate why scale characteristics that were adequate for reliably measuring the pros were not adequate for the cons. The disadvantages of using birth control or condoms may form a more complex construct that is less reliably measured by a three-item scale. To illustrate the complexity of this construct, answers to a con item may depend on the woman's experience with different types of birth control or condoms, on the attitudes and experience of present or past partners, or on the way the partners negotiate condom use. A partner's attitudes toward the use of condoms or other contraceptives may be more salient for a woman's rating of the cons than the pros. It is also possible that the advantages construct may appear less complex in this analysis because the items chosen tended to focus on aspects of safety and protection, while the items in the con scales were more divergent. The exploration of possible revisions of the con scales suggests that increasing the number of items in each scale and including items that more women agree with could improve reliability. Despite their low internal consistency, the con scales did behave as predicted in TM and thus appear to remain useful in testing the overall model. In this instance the con scale may be functioning as an index measuring the presence or absence of a list of disadvantages (similar to an index of risk characteristics), rather than as a set of items all measuring the same underlying construct. Further research testing an expanded list of con items will be needed to determine the exact 354

Self-efficacy/decisional balance for condom use nature of this construct as it pertains to birth control and condom use. This study has implications for research on difficult-to-reach populations and for data collection under demanding circumstances. The diversity of the sample of women interviewed for this study is a strength, in that the predicted patterns were found to be consistent in spite of differences in interview settings and in target populations. The measures of self-efficacy and decisional balance developed for this project, as well as the stages of change model, appear to apply equally well to high-risk women reached in service settings and to women chosen at random in their communities. Associations among the stages of change, selfefficacy, and the pros and cons for condom use with main and other partners and for birth control use suggest that interventions may be successful in promoting behavior change if they attempt to increase self-efficacy and emphasize the advantages of the behavior. Although several HTV prevention programs have focused on improving selfefficacy, few interventions that target decisional balance have been implemented and evaluated. These findings indicate that elements of TM may be effective in promoting change in sexual behavior, and that measures of self-efficacy and decisional balance are useful in evaluating preventive interventions for women at risk for HIV infection. Acknowledgments Data were collected under a Cooperative Agreement funded by the Centers for Disease Control and Prevention. Principal Investigators for the Prevention of HIV in Women and Infants Demonstration Projects are: Janet Adams, Family Health Council, Inc. (Pittsburgh); Kay A. Armstrong, Family Planning Council (Philadelphia); Ruth R. Faden, Andrea Gielen, Johns Hopkins University, School of Hygiene and Public Health (Baltimore); Jennifer Lauby, Philadelphia Health Management Corporation; Roger Lum, Alameda County Health Care Services Agency (Oakland); Geraldine Oliva, San Francisco Department of Public Health; Michael Stark, Multnomah County Health Department and Oregon Health Division (Portland); Rebecca Cabral, Christine Galavotti, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention (CDC); Bobbie Person, National Center for HTV, STD and TB Prevention, CDC (Atlanta). References Bandura, A. (1990) Perceived self-efficacy in the exercise of control over AIDS infection. Evaluation and Program Planning, 13, 9-17. Bandura, A. (1977) Self-efficacy: toward a unifying theory of behavioral change. Psychological Review, 84, 191-215. Brafford, L. J. and Beck, K. H. (1991) Development and validation of a condom self-efficacy scale for college students. Journal American College Health, 38, 219-225. Brien, T. M., Thombs, D. L., Mahoney, C. A. and Wallnau, L. (1994) Dimensions of self-efficacy among three distinct groups of condom users. Journal ofamerican College Health, 42, 167-174. Centers for Disease Control and PrevenUon (1995) HIV/AIDS Surveillance Report. CDC, Atlanta, GA. Galavotti, C, Cabral, R. J., Lansky, A., Grimley, D. M., Riley, G. E. and Prochaska, J. O. (1995) Validation of measures of condom and other contraceptive use among women at high risk for HIV infection and unintended pregnancy. Health Psychology, 14, 570-578. Grimley, D. M., Riley, G. E., Bellis, J. M. and Prochaska, J. O. (1993) Assessing decision-making and contraceptive use of men and women for the prevention of pregnancy and sexually transmitted diseases/aids. Health Education Quarterly, 20, 455-470. Janis, I. L. and Mann, L. (1977) Decision-making: A Psychological Analysis of Conflict, Choice, and Commitment. Free Press, New York. O'Leary, A. (1985) Self-efficacy and health. Behavior Research Therapy, 23,437-451. Prochaska, J. O. (1994) Strong and weak principles for progression from precontemplation to action on the basis of twelve problem behaviors. Health Psychology, 13, 47-51. Prochaska, J. O. and DiClemente, C. C. (1983) Stages and processes of self-change in smoking: toward an integrative model of change. Journal of Consulting and Clinical Psychology, 5, 390-395. Prochaska, J. O. and DiClemente, C. C. (1984) The Transtheoretical Approach: Crossing the Traditional Boundaries of Therapy. Dow Jones/lrwin, Homewood, IL. Prochaska, J. O. and DiClemente, C. C. (1986) Toward a comprehensive model of change. In Miller, W. R. and Heather, N. (eds), Treating Addictive Behaviors: Processes of Change. Plenum Press, New York. Prochaska, J. O., DiClemente, C. C. and Norcross, J. C. (1992) In search of how people change: Applications to addictive behaviors. American Psychologist, 47, 1102-1114. 355

J. L. Lauby et al. Prochaska, J. O., Velicer, W. E, Rossi, J. S., Goldstein, M. G., predicting smoking cessation. Journal of Personality and Marcus, B. H., Rakowski, W., Fiore, C, Harlow, L. L, Social Psychology, 48, 1279-1289. Redding, C. A., Rosenbloom, D. and Rossi, S. R. (1994) Wulfert, E. and Wan, C. K. (1993) Condom use: a self-efficacy Stages of change and decisional balance for twelve problem model. Health Psychology, 12, 346-353. behaviors. Health Psychology, 12, 209-214. Velicer, W. F., DiClemente, C. C, Prochaska, J. O. and Brandenbum, N. (1985) A decisional balance measure for Received on November 11, 1996; accepted on June 10, 1997 356